Compressor-controlling mechanism



Nov. '22, 1927. 1,649,900

F. D. HOLDSWORTH COMPRESSOR CONTROLLING IECHANISI Filed Mar%30. 1922Patented Nov. 22, 1927.

UNITEDv STATES 1,649,900 PATENT OFFICE.

FRED D. HOLDSWORTI-I, 0F CLAREMONT, NEW HAMPSHIRE, ASSIGNOR TO SULLIVANMACHINERY COMPANY, A CORPORATION OF MASSACHUSETTS.

COMPRESSOR-CONTROLLING MECHANISM.

Application filed March 30, 1922. Serial No. 548,131.

My invention relates to compressor controlling mechanisms, and moreparticularly to automatic means for controlling the running of acompressor and its loading at appropriate times. 7

An object of my invention is to provide an improved compressorcontrolling mechanism. Another object of my invention is to provideimproved means for controlling the starting and stopping of a compressorin accordance with the demands for compressed air and improved meanscontrolled by the starting and stopping of the compressor forcontrolling the loading and unloading of the compressor. A furtherobject of my invention is to provide improved electro-pneumatic meansfor the loading and unloading of a compressor. Other objects andadvantages of my invention will hereinafter more fully appear.

In the accompanying drawings I have shown for purposes of illustrationone form which my invention may assume in practice.

In these drawings,-

Fig. 1 is aview mainly in elevation, but partially in section, of acompressor system provided with one illustrative form of my improvedcontrolling means, the electric circuits and control means thereforbeing shown diagrammatically.

Fig. 2 is an enlarged detail view with parts shown in section, thepositions of the parts corresponding to loaded condition.

In the form of my invention which I have shown for purposes ofillustration, the same is disclosed as applied to a compressor 1 havinga cylinder 2 in whose bore 3 a piston 4. is adapted to be reciprocatedby means ofv a crank shaft 5 and operative connections (not shown). Thecompressor discharges by way of a pipe 6 to a receiver 7 throughdischarge mechanism 8 of any suitable form. The admission of air to thecompressor cylinder takes place past inlet valves 9 of familiarconstruction, these valves being normally held closed by springs 10 andopened by reason of the reduction of pressure within the piston boreduring the suction strokes of the piston. For the purpose of opening theinlet valves and maintaining them open to thereby unload the compressorwhen desired, I provide pistons 11 reciprocable in cylinders 12 to whichair may be supplled by way of a connection 13 under control of mechanism14 hereinafter more fully described, the passage 13 being connected tothe receiver by the passage 15 under control of the mechanism 14.

The compressor is driven by a motor diagrammatically shown at M, whichmotor is provided with starting means having a series of resistances 16,17, 18 and 19, all of which are in circuit when the main switch 20closes the circuit through the main wires 21 and 22 to the motor. Itwill be noted that the mainswitch 20 is controlled by a solenoid 23which is controlled by a pilot switch 24 whose movements are regulatedby a diaphragm 25 diagrammatically shown in Fig. 1, the diaphragm beingresponsive directly to receiver pressure by way of a direct connection26 to the pipe 15, it being noted that when the receiver pressure is inexcess of any predetermined desired amount, 'the pilot switch 24 will beopen, while when the pressure falls below the desired limit, the pilotswitch will close, and thereby close the main line switch 20. Themainline switch has movable therewith a supplemental switch 27 whichcontrols a circuit through a solenoid 28 which serves in turn to close aswitch 29 shunting the first resistance 16. The switch 29 carries withit a supplemental switch 30 which closes an operating circuit whichcauses the next succeeding resistance 17 to be shunted and as eachsuccessive resave that it may be stated that the movements of each ofthe resistance shunting switches are controlled by dashpot meansdiagrammatically shown at 31, these dashpots bein constructed to providea relative ly slow 0 osing movement of the switches, while permittingopening movements thereof under action of the springs 32 to be quitesharp. An examination of the connections shown will readily disclosethat opening of the main line switch will cause the instantaneousopening of all the resistance shunting switchesand so that each time themotor is stopped, it is brought up to speed by the gradual cutting outof the full resistance, it being observed that by reason of the presenceof the dashpot mechanisms described, a sufiicient time lapse between theclosing of the main line switch and the cutting out of all resistance isprovided to permit the motor to come up to substantially running speed.It will be noted that the last resistance shunting switch carries asupplemental switch 35 which closes a circult through a solenoid 36forming a part of the mechanism 14, causing energization of the solenoid36 to take place substantially when the motor has come up to full speed.

The mechanism 14 comprises a valve casing 37 having a chamber 38thereinclosed at its top by a threaded plug 39, which openin plug istraversed by a passage 40 and terminates at its inner end in a conicalvalve seat 41. Within the chamber 38 is a ball valve 42 which is adaptedto be seated upon a conical seat 43 opposite the seat 41 and to movebetween said seats under conditions which Will be described. The seat 43surrounds a passage 44 which communicates withthe connection 15. Thechamber 38 communicates with the pipe 13. Cooperat ing with the ballvalve 42 is a plunger 45 extending loosely through the passage 40- andhavin a collar 46 thereon with which a spring 4 cooperates whereby thenormal tendency of the spring is to raise the plunger 45 and to permitthe lifting of the ball 42 from the seat 43 by receiver pressure and theseating of the ball 42 upon the seat 41, thereby closing off all escapeof air through the passage 40. The plunger 45 is provided with anarmature 48 which is attracted by the solenoid 36 so that upon supplfyof current to the solenoid upon closure 0 the switch 35, the armature 48will be drawn downward, moving the plunger 45 with it and forcing theball 42 to the seat 43 and the passage 40. It will therefore be evi outthat when the solenoid 36 is energized, receiver pressure will not beper mitted to pass through the pipe 13 to the cylinders 12, but insteada vent 40 will be opened and any pressure will be permitted to pass fromthe cylinders 12 t0 the atmosphere. 7

From the foregoing description, the mode of operation of theillustrative form of my invention will be readily understood. Let it beassumed that the parts are in the position shown in Fig. 1. It will beevident that the inlet valves are being held open since, there being nocurrent flowing through the solenoid 36, the receiver pressure acting upon the valve 42 and the spring 47 lifting the plunger 45 will serve topermit opening of the valve 42 in such manner as to connect the receiverand the lower ends of the cylinders 12. The compressor will according-1%; be unloaded and the motor idle. As t e receiver pressure drops dueto air consumption, leakage, etc., the diaphragm25 will move toward theright in Fi 1 and close the pilot switch 24 and there y cause closing ofthe main switch 20 and the starting and gradual bringing up to speed ofthe motor M. When the resistance has been cut out by the mechanismdescribed, the switch 35 will close the circuit through the solenoid 36and the latter bein ener 'zed will move the armature 48 to orce own theplunger 45 and so close communication between the receiver and theplungers 11, while openin the vent through the port 40. It will thus lieseen that the compressor is loaded automatically substantially as fullrunning speed is reached and that current economy is assured and the aparatus safeguarded by the avoidance 0 drawing a heavy current to startunder full load.

It will be obvious to one skilled in the art, that my improvedcontrolling mechanism can be adapted to use with intake type unloadingmechanisms and that,'if desired, various modifications can be madewithin the scope of my invention as defined in the appended claim.

While I have in this application specifically described one form which minvention may assume in practice, it wil be understood that this form ofthe same is shown for purposes of illustration and that the inventionmay be modified and embodied What I claim as new and desire to secure byLetters Patent is:

In a compressor controlling system, a controlling valve mechanismcomprising a casing member having a recess formed therein, said recesscommunicating freely With a con nection to a space in which variationsin pressure are desired and having also a'connection surrounded by avalve seat leading to a source of fluid pressure, a plu extending intoand closing said recess, sai plug being disposed opposite said valveseat and having formed thereon a valve seat oppositely disposed withrespect to said first mentioned valve seat, said plug being traversed bya port communicating with said secondmentioned valve seat, a plungerextending through said port and of smaller diameter than said port, aspring normally'tending to force said plunger out of said port, asolenoid operative on energization'to move said plunger inward throughsaid port in opposition to said spring, and a ball valve disposed insaid recess and moved in opposite directions by said sure from saidsource. i

In testimony whereof I aflix mysignature.

FRED D. HOLDSWORTH.

